Nowadays, an electronic circuit board is used in every product, performance of the electronic circuit board is improved day by day, and a frequency used on the circuit board is high. Flip-chip mounting with low impedance is a mounting method suitable for an electronic apparatus that uses a high frequency. According to an increase of portable apparatuses, there is a demand for flip-chip mounting for mounting an IC chip on a circuit board in a bare state rather than a package. Besides the flip-chip, a CSP (Chip Size Package), a BGA (Ball Grid Array), and the like are used.
In the past, as a method of joining an electronic component such as an IC chip to a circuit board of an electronic apparatus, there is proposed as method of connecting electrodes of the electronic component and electrodes of the circuit board with projection bumps made by using an Au line, sealing the electrodes with a sheet or paste made of insulating resin, heating and pressing the insulating resin to cure the insulating resin, and manufacturing an electronic component mounting structure (see, for example, Japanese Patent Application Laid-Open No. 2004-312051).
In FIGS. 8(a) to 8(c), sectional schematic views for explaining the method of manufacturing a mounting structure in the past proposed in Japanese Patent Application Laid-Open No. 2004-312051 are shown. In FIGS. 8(a) to 8(c), the shape of bumps 103 is schematically represented.
As shown in FIG. 8(a), the bumps 103 are formed on electrodes 102 of an IC chip (electronic component) 101 in advance by using an Au line. Electrodes 105 are provided on both sides of a circuit board 104.
As shown in FIG. 8(a), a paste-like thermosetting insulating resin 106 is applied on the circuit board 104 side, the bumps 103 formed on the IC chip 101 attracted and held by a joining tool 100 is aligned to be opposed to the electrodes 105 of the circuit board 104, the joining tool 100 is lowered, and, as shown in FIG. 8(b), the IC chip 101 is mounted in such a degree that the bumps 103 and the electrodes 105 opposed thereto are lightly set in contact with each other. In FIG. 8(a), instead of applying the paste-like insulating resin to the circuit board 104 as the insulating resin 106, sheet-like insulating resin may be stuck to the circuit board 104.
Thereafter, as shown in FIG. 8(c), a heated heating and pressing tool 107 is pressed on the IC chip 101 to simultaneously perform heating and pressing and the electrodes 102 of the IC chip 101 and the electrodes 105 of the circuit board 104 are joined by the bumps 103. The insulating resin 106 is cured by the heating at this point and a space between the IC chip 101 and the circuit board 104 is sealed.
In this way, the method of manufacturing a mounting structure in the past is divided into a mounting stage shown in FIGS. 8(a) and 8(b) and a joining stage shown in FIG. 8(c).